This invention relates to an automatically opened and closed barrel for use in plating, chemical conversion coating, etc. This barrel is so designed that a lid is opened only when the barrel must be kept open, otherwise the lid is kept closed.
Generally, barrels are used for a plating treatment. The barrel for a plating treatment has an opening through which material to be treated is put in and treated material is taken out. This opening is provided with a lid by which it is closed. This lid is of either screw type or lever type. Whenever material to be treated is put in or treated material is taken out, a screw or a lever is loosened for opening the lid and later is tightened for closing the lid. Thus, the lid opening and closing operation must be done manually and such manual operation is troublesome.
In order to improve the opening and closing operation of a lid of a barrel, the present applicant previously devised a barrel having a lid which is automatically opened and closed and applied to the Japanese Patent Office for a patent for such device. This patent application was published in the Official Patent Gazette (Japanese Utility Model Registration Application Publication No. 54-14728). This automatic lid opening and closing device for a barrel is characterized in that a lid is hinged to one of the edges of the opening of a barrel in such a fashion that it swings only within the barrel itself and a lever is provided at a hinge shaft. This lever is worked by a guide bar in response to the normal or the reverse rotation of a barrel for keeping the lid in a closed state or in an opened state. Thus, material to be treated can be put in or treated material can be taken out of the barrel, without the necessity of hands, and various treatments can be carried out continuously and automatically.
In the case where the automatically opened and closed barrel mentioned above is used for a plating treatment, Applicant's previously devised barrel is completely suitable. However, it has recently been suggested to use barrels for a chemical conversion coating treatment of parts, for example, as well as plating treatments. As compared with the parts for which a plating treatment is given, parts of machine tools and others are larger in size and heavier in weight. At present, in the case of the chemical conversion treatment, material to be treated is put in a cage having an opening at the top surface thereof and the cage is hung down or hung up by a hoist crane or the like into or from a treating liquid tank. Mere immersing of a cage containing material to be treated in a treating liquid tank does not give a uniform chemical conversion treatment to the outer surface of the parts, especially when the parts are of complicated construction. In this connection, it is imaginable that a uniform treatment can be carried out if material to be treated is put in a barrel and the barrel is rotated. However, material to be treated is often heavy in weight, and the barrel which is normally made of synthetic resin when used for a plating treatment is of an inadequate strength. Therefore, it is required to manufacture barrels with chemical resistant metal, such as stainless steel. When the barrel is formed of metal, however, the weight of its lid becomes heavier, and if the construction of a conventional automatic opening and closing type barrel is adopted, the lid will swing at each rotation of the barrel. Consequently a cam for opening and closing the lid and a lever which is slid by such cam will be broken.